[TechAssist] RCA P52937 / PTK195M3B Projo. no sound,FIX]
- From: Philip Bader <tjanphyl@xxxxxxxxxxxxxxx>
- To: "techassist@xxxxxxxxxxxxx" <techassist@xxxxxxxxxxxxx>
- Date: Mon, 25 Aug 2003 17:18:57 -0400
After hooking up my chipper check (an experience) I determined the
eeprom was not at fault.I downloaded customer's EEPROM settings for safe
keeping in the chipper check program.
I noticed at the AC cord input the spark gap in the circuit board gad
been hit hard.A good arc-over.
Further inspection found the Stereo output amp IC U11901 had a small
crack in it's body. Part# TDA7499/RCA# 235446. Replaced it, but still no
sound. The IC's Vcc pin 3 was zero volts. Should be +31 VDC from source
"+31Vs <20-B>".
This 31 Volt source originates from SMPS transformer T14101 pin 11, thru
diode D14116, thru 3 watt resistor R14153 (2 ohm,3W). My version did not
show L14101 in paralell,must be a defferent version. The 2 ohm was
open.Replaced resistor, +31V restored.
Sound restored.
Fix: U11901 audio output and Vcc source PS resistor R14153.
Done.
Philip Bader
PS: a bit about chipper check:
I downloaded the eeprom parameters for safe keeping,then wanted to
"initialise" the eeprom to see if it became corrupted and this would
restore sound.It asked me what software version the micro was running,
"Gold program gemstar guide detected", does customer have "gold" or
"standard"...
GEEZ I did'nt know those things.Other items asked for yes/no answers
before continuing.
I assume this affected HOW the eeprom is initialised.I thought a wrong
entry may cause troubles with certain options and functions, so I bailed
out. Either this CC program is stupid, or I am.Thought it was supposed
to look into the thing and find out for itself!
Well, It's done.NO thanks to Chipper Check.
P.B.
Tried unplugging it, went into menu and made sure the speakers were
selected "on".The sound OSD bar moves but no sound at all not a
whisper.Picture seems unaffected.(slight bow or trapaziod was seen in
home but that may be unrelated and almost un-noticable. Seemed to happen
about a week after a major lightning strike near their home.
Need input!
Phil Bader
--
Philip Bader
Jan Phyl TV Inc. (estab. 1976)
3420 Recker Hwy. Winter Haven, Fl. 33880
Fax (863) 299-8821
email: tjanphyl@xxxxxxxxxxxxxxx
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